| 'Greek letter alpha' | angular acceleration; first [carbon atom next to the carbon atom bearing the active group in organic... |
|---|---|
| C1a | activated first component of complement |
| C1 INH | inhibitor of first component of complement |
| CI | first cranial nerve |
| CN | I to XII first to twelfth cranial nerves |
| first molar | First permanent molar, sixth permanent tooth or fourth deciduous tooth in the maxilla and mandible on either side of the midsagittal plane of the head following the arch form. (05 Mar 2000) |
|---|---|
| first-order kinetics | A term describing the reaction rate of a chemical reaction in which the rate is proportional to the concentration (in moles) of only one of the reactants. Such a reaction might have an equation like rate = k[A], where k is the reaction rate constant and [A] is the concentration of a reactant A. (09 Oct 1997) |
| first-order reaction | A reaction the rate of which is proportional to the concentration of the single substance undergoing change; radioactive decay is a first-order process, defined by the equation -(dN/dt)=kN, where N is the number of atoms subject to decay (reaction), t is time, and k is the first-order decay (reaction) constant, i.e., the fraction of all atoms decaying per unit of time. See: decay constant, order. (05 Mar 2000) |
| first parallel pelvic plane | The upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. Synonym: apertura pelvis superior, aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic inlet, pelvic plane of inlet, plane of inlet. (05 Mar 2000) |
| first rank symptoms | Those symptom's that, when present, indicate that the diagnosis of schizophrenia is likely, provided that organic or toxic aetiology is ruled out: delusion of control, thought broadcasting, thought withdrawal, thought insertion, hearing one's thoughts spoken aloud, auditory hallucinations that comment on one's behaviour, and auditory hallucinations in which two voices carry on a conversation. Synonym: first rank symptoms, schneiderian first rank symptoms. (05 Mar 2000) |
| first-set rejection | Allograft transplantation between two organisms not previously sensitised to the graft tissue. Necrosis of the graft usually occurs within 10 days of transplantation. (05 Mar 2000) |
| first stage of labour | The part of labour when the cervix dilates fully (to 10 centimeters). The first stage of labour is also called the stage of dilatation. (12 Dec 1998) |
| first temporal convolution | A longitudinal gyrus on the lateral surface of the temporal lobe between the lateral (sylvian) fissure and the superior temporal sulcus. Synonym: gyrus temporalis superior, first temporal convolution, superior temporal convolution. (05 Mar 2000) |
| first visceral cleft | <anatomy> The cleft between the hyoid and mandibular arches of the embryo; the external auditory meatus is developed from its dorsal portion. Synonym: first visceral cleft. (05 Mar 2000) |
| bone within a bone | <radiology> STOP heavy metal, S: sickle cell disease, T: Thorotrast, O: osteopetrosis, P: Paget's disease, heavy metals, hypervitaminosis D (12 Dec 1998) |
| acute reflex bone atrophy | Atrophy of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. See: causalgia, reflex sympathetic dystrophy. Synonym: acute reflex bone atrophy, posttraumatic osteoporosis, Sudeck's syndrome. Origin: L. English sweat (05 Mar 2000) |
| air-bone gap | The difference between the threshold for hearing acuity by bone conduction and by air conduction. (05 Mar 2000) |
| Albrecht's bone | A small bone between the basioccipital and basisphenoid. (05 Mar 2000) |
| allogeneic bone marrow transplant | <haematology, procedure> A bone marrow transplant using marrow collected from a matched healthy donor, usually a brother or sister. The risks associated with the transplant increase with age and 50 years of age is generally regarded as the upper limit. (13 Nov 1997) |
| alveolar bone | That portion of bone in either the maxilla or the mandible which surrounds and supports the teeth. (12 Dec 1998) |